Tube retainer for a mask



FIG. 1 is a front perspective view of a tube retainer for a mask according to our design;

FIG. 2 is a front view thereof with the rear view being identical;

FIG. 3 is a top view thereof;

FIG. 4 is a bottom view thereof; and,

FIG. 5 is a left side view thereof with the right side view being identical. 

CLAIM The ornamental design for a tube retainer for a mask, as shown. 